The Experience Corps (EC) is a community-based, health promotion model for older adults, embedded in a social engagement program designed to improve academic and behavioral outcomes of children in public elementary schools. With P01 funding we are conducting a 5-year randomized controlled effectiveness trial (RCT) of the impact of this program on older adults'health and function, as well as assessing the program's impact on schools and children. This competitive supplement proposes implementation of a study to monitor and improve the fidelity of the EC program, as recommended by the reviewers of our original P01 application. Data collected through this proposed fidelity study will allow for empirical evaluation of intervention fidelity as part of the evaluation of RCT findings. To date, administrative supplements provided funding to monitor the initial implementation of selected aspects of the training and intervention during Yr 01;and to begin developing data entry/management applications and monitor the controls in Yr 02. The current application outlines a formal plan to monitor and enhance implementation fidelity throughout the course of the trial, following "best practice" recommendations set forth by Bellg, Borrelli et al. (2004). Proposed fidelity monitoring includes three components - (1) monitoring the training that older adult volunteers receive before they are placed in the schools and in-service training and refresher training after they are placed in the schools, as well as monitoring training for EC site coordinators, teachers, and principals who have EC volunteers in their schools;(2) monitoring the on-going EC activities of the volunteers in the schools (i.e., the actual intervention itself) along with parallel monitoring of control activities;and (3) studying the organizational and contextual factors that may impact overall program implementation and RCT outcomes. We also propose to monitor the experience of principals, teachers, and administrative staff in intervention and control schools of serving as an EC or non-EC school. In sum, the specific aims of this competitive supplement are to augment existing, P01-funded data collection to include assessment and analysis of the level of implementation of the EC-RCT. These data will provide additional crucial information - missing from current P01-funded data collection - about fidelity of program implementation, thereby allowing for evaluation (and modification) of not only factors that may impact the fidelity of training/intervention, but also of possible reasons for positive (or negative) findings with respect to the P01-funded EC-RCT's primary outcomes.